Experimental investigation on the axial static and cyclic response of a single pile in medium-dense sands

Abstract

Cyclic loads induced by environmental factors such as wind, waves, and currents can lead to degradation in pile performance, affecting settlement accumulation and bearing capacity evolution. This paper presents a comprehensive investigation through model tests focusing on a single pile subjected to static and cyclic loading in medium-dense sands. The influence of installation method, diameter, cyclic load amplitude, and loading frequency on pile response was explored, particularly emphasizing the accumulation pattern of pile head settlement and the evolving laws governing pile shaft and end resistance. The findings illustrate that the radial stress at the pile shaft 400 mm away from the pile end increases to 3.27 times its initial stress after pile jacking. As pile diameter increases, the accumulative settlement rate decreases, highlighting the soil-squeezing effect on cyclic stability. Small cyclic loads gradually densify soil around the pile end, increasing pile end resistance, while larger cyclic loads rapidly reduce both pile end and shaft resistance. Under high-amplitude, low-frequency cyclic loading, the load-settlement hysteresis characteristics of model piles intensify, with the hysteresis loops moving more rapidly in the deformation direction.